Update design spec with implementation notes covering recursive
compound nesting, edge z-ordering, ON_COMPLETION sections, drill-down
navigation, CSS transform zoom, and HTML overlay toolbar.
Increase SECTION_GAP to 80px for better visual separation between
completion and error handler sections.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
b1ff05439a